Electronic Commuta-tion with Position Encoders Rotary encoders with commuta-tion signals ). When these encoders are mounted, the rotor positions of the encoder must be assigned to those of the motor in order to ensure the most constant possible motor current. Inade-quate assignment to the motor emf will cause loud motor noises and high power loss. Rotary encoders with integral bearing are aligned approximately—for example with the aid of the line mark-ers on the encoder or the reference mark signal—and mounted on the motor shaft. The fi ne adjustment is quite easy with a PWM 9 phase angle measuring device (see First, the rotor of the motor is brought to a preferred position by the application of a dc current. HEIDENHAIN Measuring and
Testing devices Absolute rotary encod-ers are at fi rst mounted as a complete unit. Then the preferred position of the motor is assigned the value zero. The IK 215 adapter card for PCs and the accompanying soft-
ware (see ): the stator of the encoder is turned until the PWM 9 displays, for exam-
ple, the value zero as the distance from the reference mark.
Synchronous motors require information on the rotor position immediately after switch-on. This information can be provided by rotary encoders with additional commu-
tation signals, which provide relatively rough position information. Also suitable are absolute rotary encoders in multiturn and singleturn versions, which transmit the exact position information within a few sec-
onds of arc (see also Rotary encoders without integral bearing HEIDENHAIN Measuring and Testing Devices ) serve this purpose. They feature the complete range of EnDat func-
tions and make it possible to shift datums, set write protection against unintentional changes in saved values, and use further inspection functions. ECI/EQI rotary encoders are mounted as complete units and then adjusted with the aid of the IK 215 adapter card for PCs and the accompanying software. For the ECI/
EQI 1300, the central screw is loosened again and the encoder rotor is turned with the mounting aid to the desired position until, for example, an absolute value of ap-
proximately zero appears in the position data. The stator housing of the ECI/EQI 1100 must be turned. For the ECI/EQI with pure serial operation (EnDat 21), elec-
tronic compensation is also possible: the ascertained compensation value is saved in the encoder and can be read out by the control electronics to calculate the position value.
Motor current of adjusted and very poorly adjusted rotary encoder
Aligning the rotary encoder to the motor emf with the aid of the adjusting and testing software for the IK 215
Manual alignment of ECI/EQI 1300
Encoder adjustedEncoder very poorly adjusted
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